Bipolar plate

Abstract

A bipolar plate has a first inlet port and a flow field comprising a plurality of ducts to connect the first inlet port to a first outlet port for a first reactant, and has a second inlet port and a flow field comprising a plurality of ducts to connect the second inlet port to a second outlet port for a second reactant, wherein at least one bypass duct is present at the margin of at least one of the flow fields. The bypass duct is associated with at least one flow connection branching off from the bypass duct into an adjacent marginal duct of the flow field.

The invention claimed is: 
     
       1. A bipolar plate, comprising:
 a first inlet port; 
 a first flow field comprising a first plurality of ducts to connect the first inlet port to a first outlet port for a first reactant; 
 a second inlet port; and 
 a second flow field comprising a second plurality of ducts to connect the second inlet port to a second outlet port for a second reactant; 
 wherein at least one bypass duct is present at the margin of at least one of the flow fields; 
 wherein the bypass duct is associated with at least one flow connection branching off from the bypass duct into an adjacent marginal duct of the at least one of the flow fields; and 
 wherein a bypass blocker is arranged in the at least one bypass duct upstream from the outlet port to assist in directing reactant flow through the at least one flow connection to the adjacent marginal duct of the at least one of the flow fields. 
 
     
     
       2. The bipolar plate according to  claim 1 , wherein both of the first and second flow fields and at least one respective bypass duct are present on either side of the bipolar plate, and wherein at least one respective flow connection branches off from each of the bypass ducts into a respective adjacent marginal duct. 
     
     
       3. The bipolar plate according to  claim 1 , wherein the at least one flow connection is provided in a half of the flow field adjacent to the outlet port. 
     
     
       4. The bipolar plate according to  claim 1 , wherein the at least one bypass duct is associated with multiple flow connections, which are configured at a spacing from each other in the flow direction. 
     
     
       5. The bipolar plate according to  claim 1 , wherein a marginal duct connection to an adjacent duct of the flow field is provided in the marginal duct downstream from the flow connection. 
     
     
       6. The bipolar plate according to  claim 5 , wherein respective adjacent ducts have a duct connection downstream from the marginal duct connection in the flow field. 
     
     
       7. The bipolar plate according to  claim 6 , wherein the marginal duct connection and/or the duct connection is realized by a reduction of the web height. 
     
     
       8. The bipolar plate according to  claim 1 , wherein the ducts of the flow field and the bypass duct are separated from each other by webs, and the flow connection is realized by a reduction of a web height of the web between the bypass duct and the adjacent marginal duct. 
     
     
       9. The bipolar plate according to  claim 8 , wherein the web height is entirely reduced. 
     
     
       10. A bipolar plate of a fuel cell, the bipolar plate comprising:
 an inlet port; 
 an outlet port; 
 a flow field comprising a plurality of ducts that connect the inlet port to the outlet port for distributing a reactant within an active region of the bipolar plate during operation of the fuel cell; and 
 at least one bypass duct that extends alongside the flow field at a margin of the flow field outside the active region of the bipolar plate; 
 wherein the bypass duct is associated with one or more flow connections branching off from the bypass duct into an adjacent marginal duct of the flow field; and 
 wherein the one or more flow connections are provided only in a downstream half of the flow field adjacent to the outlet port.